Carboxyl containing polymers of vinylidene monomers containing at least one terminal CH.sub.2 &lt; group are well known. Such polymers may be homopolymers, or copolymers with other vinylidene monomers, of unsaturated polymerizable carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, itaconic acid and the like. Often copolymers of these acids are cross-linked with small amounts of cross-linking agents, which in the form of their salts absorb large quantities of water or solvents. These materials are normally prepared by polymerization with a free radical catalyst in an organic medium in a closed vessel or autoclave equipment with stirring. These carboxyl containing polymers prepared in organic media are unstable and at least part of the polymers form deposits on the wall of the reactor during each polymerization. As such deposits build up it becomes difficult to remove heat from the polymerization reaction that is ncessary to control the properties of the polymer, and this requires frequent cleaning of the reactors. After a number of polymerizations, the reactor surfaces are so extensively fouled with polymer deposits as to be extremely difficult to clean. One cleaning method presently used, after about 60 or 70 polymerization charges to prepare cross-linked polyacrylic esters of the type described in U.S. Pat. No. 2,978,053, is to fill the reactor with heated concentrated sodium hydroxide solution. It normally requires from 14 to 30 days to satisfactorily remove the polymer deposits from the reactor wall. This expensive and time consuming operation effectively removes from production each reactor being cleaned for a two to four week period. An improved cleaning process to remove carboxyl containing polymer deposits from reactor walls is desired.